Every move you make, every step you take, you're generating energy. At least some of it goes to waste. A couple of years ago, a team of engineering doctoral candidates at Northwestern University—all three were runners and, of course, smartphone users—set out to cash in on this untapped kinetic energy in everyday life.

Their classroom project turned into an Evanston startup they dubbed Ampy, a wordplay on the measure of current, and the Move, a rechargeable lithium-ion battery pack that hit the market in September.

The $99 device, modeled on a hip flask, can be worn on arms, legs or a belt to collect and store energy you produce by running, cycling or participating in a sport. The Move is sweatproof but isn't immersible, though swimmers have adapted it with a protective bag. The Move weighs 5.5 ounces and comes with USB and micro-USB cables to transfer power to smartphones and fitness devices.

Each hour of rigorous exercise produces enough electricity to power a smartphone for an hour, Ampy promises on its website, GetAmpy.com.

Ampy CEO Tejas Shastry predicts first-year sales will reach $6 million to $7 million on volume of 80,000 units.

In addition to Shastry, 26, who is from the Peoria area, Ampy's co-founders are Alex Smith, 30, chief product officer, of suburban Sacramento, Calif., and Mike Geier, 29, chief technology officer, from the Bay Area. The company has three other employees.

Amy Francetic, CEO of the Clean Energy Trust, a nonprofit accelerator for startups in the Midwest, was the team's adviser in the NUvention class at Northwestern's Farley Center for Entrepreneurship and Innovation in 2013. Often, she says, students are working on developing a professor's research. “I was impressed from the beginning that the device was their idea based on their personal desires and challenges like classic entrepreneurs,” she says.

The project won $75,000 in the trust's startup competition in 2014. Ampy went on to raise $309,000 through a Kickstarter campaign, three times the founders' goal. In October, Ampy received $875,000 in seed funding from the trust, NewGen Venture Partners of Palo Alto, Calif., and a group of angel investors including 1871 CEO Howard Tullman, FeedBurner co-founder Steve Olechowski and John DiNardi, founder of LED lighting-maker Norlux in Carol Stream.

Kinetic-energy storage devices are not new. The foot-powered potter's wheel, which captures kinetic energy, has been around for thousands of years. More recently, inventors created chargers powered by foot pedals, hand cranks and even yo-yos. But the devices often were bulky or didn't produce much electricity.

Geier, who previously worked at a lithium battery startup, says the company hopes to sell the Move in a big-box electronics or sporting goods store. Meantime, Shastry says, Ampy is developing a Move 2.0, which would generate more power and be sleeker. “We are also working on shrinking the technology inside to incorporate it into smartwatches, fitness trackers, smart garments and on other wearable devices,” he says.